A JP Patent Publication (Kokai) No. 9-15225 A (1997) discloses a method for classifying lipoprotein particles contained in a subject sample according to the particle size by means of gel filtration liquid chromatography and then for quantifying cholesterol or triglycerides being contained in the classified lipoproteins, wherein the lipoprotein particles are fractionated into chylomicrons, very low density lipoproteins, low density lipoproteins, and high density lipoproteins by subjecting the obtained chromatogram to data processing such as a Gaussian distribution approximation.
A JP Patent Publication (Kokai) No. 2002-139501 A discloses a method for classifying lipoproteins contained in a subject sample according to the particle size by means of gel filtration liquid chromatography and then for quantifying cholesterol or t triglycerides being contained in the classified lipoproteins, wherein the lipoprotein particles are classified into 20 subclasses.
However, the classifying method disclosed in the Patent Document 2 has been applied only to a case where a specific column is used, and respective peak positions for the 20 subclasses (i.e. particle size) have not been supported with theoretical foundation. For example, a particle size of LDL (low density lipoproteins) is determined to be 25.5 nm as a cutoff value when a GGE method (polyacrylamide density gradient gel electrophoresis) is used, and is determined to be about 20 nm based on a size observed by an electron microscope when a NMR method is used, and is determined to be 25.5 nm based on a size obtained by a GGE method when a gel filtration FPLC method is used, and is also determined to be 25.5 nm based on a latex bead or globular proteins when a gel filtration HPLC is used. The particle size may vary depending on ways of estimation when a light scattering method is used. In addition, this particle size may become a different value by determining a molecular weight in accordance with equilibrium ultracentrifugation. Therefore, definition of the lipoprotein subclasses based on the particle size and comparison of respective lipoproteins contained in a subject sample between these subclasses will lead to confusion.